TROPICAL DISTURBANCE INVEST 94L FORECAST SYNOPSIS…ISSUED JUL. 03, 2017…2:50 P.M. EDT

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(T. F. “Storm” Walsh III)

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STORM W’s SEASONAL HURRICANE FORECAST
TOTAL STORMS: 14-16
HURRICANES:       6-8
MAJ. HURRICANES: 3-4

CURRENT TOTALS
STORMS: 3
HURRICANES: 0
MAJ. HURRICANES: 0

U.S. LANDFALLS: 1

Good day all!

The tropical wave located in the central Atlantic, located approximately 650 WSW of the Cabo Verde Islands, has been designated INVEST 94L.  The system is currently moving just south of due west at about 4 mph, or nearly stationary.  The NHC has designated a HIGH probability (70%) for tropical cyclone development over the next 5 days.

NHC GRAPHICAL 5 DAY TROPICAL WEATHER OUTLOOK

Based on the 12Z ATCF BTK product, the following information was available on INVEST 94L:

8:00 AM AST Mon. Jul 03
LOCATION: 9.0N…32.4W
MOVEMENT: NEARLY STATIONARY
PRESSURE: 1011 mb / 29.85 in
MAX SUSTAINED WIND: 30 mph

Analysis of satellite loop imagery this morning indicates the disturbance appears to be getting slowly better organized.

RAMSDIS METEOSAT FLOATER LOOP IMAGERY (CLICK FOR ANIMATION)

A review of loop imagery for the past 2 days reveals, that the original AOI and the wave I mentioned yesterday which had just exited the African coast, may have been a part of one large, broad area within the West African Monsoon Circulation, and appears to now have formed one area.

Current maximum winds are estimated to be near 30 mph.  Analysis of the current wind shear products indicate that 94L is currently located in  an area where wind shear/upper level winds are marginally conducive at the moment.  Partial divergence aloft was noted, albeit there is no established outflow channel/jet at the moment.  The divergence which is taking place, is attributed to the system sitting east of a TUTT (Tropical Upper Tropospheric Trough), indicated by the arrow pointing to the trof axis.  You can follow the brown streamlines from there, which arc in a semi clockwise fashion.

CURRENT WIND SHEAR FROM CIMSS

Based on the current wind shear forecast from the GFS, upper level winds are forecast to become favorable, or conducive for development within the next 36 – 48 hours, with an upper level anticyclone forecast to develop over the system.  This feature is forecast to move in tandem with the system through to day 5.  By day 6 (138 – 144 hours) this feature begins to collapse, and almost dissipates in day 7.  By day 8.5 – 10, the upper level feature is forecast to become re-established.

GFS WIND SHEAR FORECAST (BROWN ARROW 94L LOCATION)


Analysis of current and forecast PWAT, RH850 (Relative Humidity @ the 850 mb level), and RH700 (RH @ 700 MB) indicate favorable values through 10 days.  However, currently, there is a good portion of dry air to the north of the system.  Thus far, the dry air hasn’t seemed to make much of a negative impact, which is probably due to the PW levels surrounding 94L in a limited area around the circulation.  My thoughts at the moment on this is, 94L is in fairly weak steering currents right now…this may allow for the drier air to move away from the system before it has a negative impact.  Based on analysis of all these parameters, INVEST 94L should to continue to slowly close off a surface circulation, and should convection increase near or over the center, we may see a tropical depression during the next 36 – 48 hours.  PWAT = Total Precipitable Water.  OHC = Ocean Heat Content.

94L PWAT, DRY AIR, AND OHC

Analysis of initial intensity guidance indicates the most used models for intensity, show 94L attaining strong T.S. to CAT 1 Hurricane status in 96 hours.  Based on the forecast information at hand (given if the model information is accurate), I cannot rule this out at the moment, though I am more inclined to prefer T.S. status at the moment until I can see what happens with the current dry air situation.

12Z INTENSITY GUIDANCE

INVEST 94L is currently within a very weak steering regime.  However, within 24-36 hours from 12Z this morning, steering current are supposed to strengthen, and 94L should begin to move more toward the west-northwest (WNW).  Based on forecast steering, a weakness in the sub-tropical ridge is supposed to strengthen, as a trof digs down over the SEUS in about 4-5 days.  The current weakness is shown in the current steering layers map, where the arrow points.

CURRENT STEERING LAYERS MAP

Based on forecast steering, I have to agree with the current dynamic model guidance, and prefer the TVCA track, which is identical to the TVCN model.  THIS IS CONSIDERED TO BE PRELIMINARY however, as steering can change.  My reasoning behind this at the moemnt is, the GFS begins to re-curve this system in the northern Bahamas area,  the CMC brings it into FL., and the ECMWF indicates it could come a little further west, or stall.  The GFS is showing more of a weakness near the U.S. east coast, while the ECMWF mean indicates rising pressure heights, north of the system.  Of course, this will most likely change a few times, as we’ve seen earlier this season. IF and WHEN this system becomes better organized, we should better model guidance regarding forecast track.  I will continue to monitor this system over the next 2 days for any significant changes.

12Z DYNAMIC MODEL GUIDANCE (CLICK FOR LARGER IMAGE)

GFS

CMC

ECMWF HEIGHT ANOMALIES

Elsewhere, we may see better conditions over the Atlantic basin most likely sometime after mid month, as the MJO is forecast to continue to propagate eastward, and 200 mb vertical velocity potentials are forecast to become a little more favorable.

MJO FORECAST

200 MB VELOCITY POTENTIAL FOR JUN. 17
Elsewhere, Tropical Storm formation is not expected during the next 7-10 days.

Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS
CoCoRAHS OBSERVER

 

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About palmharborforecastcenter

I am a Tropical Forecast meteorologist, providing hurricane forecasts during the Atlantic Hurricane Season. I retired from the U.S. Coast Guard in July of 2001. Meteorology became my passion in high school, and I have continued my educational background in meteorology since 1996, when I undertook the study of Tropical Meteorology. While working toward my degree, I had to unexpectedly withdraw from college due to my oldest sons medical reasons. I do however, meet the educational criteria of the AMS to be recognized as a meteorologist. Studies include, but are not limited to the Navy Aerographers Mate course, Naval METOC meteorology course, Meteorology 2010 Sophomore level course while attending St. Petersburg College, Clearwater, FL., Basic Forecasting course for operational meteorologists from Rapid WX, meteorology institute, a four month meteorological internship, and extensive research on numerous meteorological topics such as the MJO, NAO, satellite imagery interpretation, etc. I have been forecasting Tropical Weather (Tropical Storms and Hurricanes) since 1996, with my main client being three different Coast Guard Commands.
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5 Responses to TROPICAL DISTURBANCE INVEST 94L FORECAST SYNOPSIS…ISSUED JUL. 03, 2017…2:50 P.M. EDT

  1. Diane Jacobs says:

    Thanks! Was thinking it’s too early to get anything but realize we always have to pay attention living in Florida. Have a Happy 4th today!

  2. Elliot Lisak says:

    HI Storm.
    Great synopsis. Thank you for working for us. I had accidentally deleted you and and have tried numerous times to get back on. Have I missed something. Not receiving your posts is like missing coffee in the morning

    Thank You,
    e

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